Effects of exogenous N and endogenous nutrients on alpine tundra litter decomposition in an area of high nitrogen deposition

Yingjie Zhang; Yinghua Jin; Jiawei Xu; Hongshi He; Yan Tao; Zhipeng Yang; Yunyu Bai

doi:10.1016/j.scitotenv.2021.150388

Effects of exogenous N and endogenous nutrients on alpine tundra litter decomposition in an area of high nitrogen deposition

Sci Total Environ. 2022 Jan 20:805:150388. doi: 10.1016/j.scitotenv.2021.150388. Epub 2021 Sep 17.

Authors

Yingjie Zhang¹, Yinghua Jin², Jiawei Xu³, Hongshi He⁴, Yan Tao⁵, Zhipeng Yang⁶, Yunyu Bai⁷

Affiliations

¹ Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China. Electronic address: zhangyj486@nenu.edu.cn.
² Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China. Electronic address: jinyh796@nenu.edu.cn.
³ Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China. Electronic address: xujw634@nenu.edu.cn.
⁴ School of Natural Resources, University of Missouri, Columbia, MO 65211, USA. Electronic address: heh@missouri.edu.
⁵ Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China. Electronic address: taoy431@nenu.edu.cn.
⁶ Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China. Electronic address: yangzp315@nenu.edu.cn.
⁷ Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun 130024, China. Electronic address: baiyy430@nenu.edu.cn.

PMID: 34818765
DOI: 10.1016/j.scitotenv.2021.150388

Abstract

The effects of N deposition on the C and N cycles via altered litter decomposition rates are an important aspect of global environmental change. The Changbai Mountain region experienced a high N deposition (2.7 g·m^-2·year^-1 in 2015) and corresponding expansion of Deyeuxia purpurea into the alpine tundra, resulting in changes in endogenous nutrients. However, the relative contributions of the N deposition and endogenous litter nutrients to litter decompositions remain unclear. Therefore, a 5-year N addition and 2-year litter decomposition experiments were conducted. Exogenous N reduced the remaining litter mass of Rhododendron aureum at the early stage (30-240 d) by promoting soluble sugar release, and increased it at the late stage (360-720 d) by suppressing lignin release and decreasing soil microbial community and enzyme activity. A higher proportion of D. purpurea litter (representing higher N, lower lignin, and C:N ratio) decreased remaining litter mass and increased net N release. Exogenous N decreased decomposition rate from 0.32 to 0.21 and net N release from 34% to 24%, whereas litter compositions increased decomposition rates from 0.32 to 0.69 and net litter N release from 34% to 69%. Endogenous litter nutrients directly explained 62% and 40% of the litter decomposition and net N release variables, respectively, whereas exogenous N indirectly explained 12% and 9%, respectively. Thus, we infer that the reductions in C and N storage following D. purpurea expansion may offset the increases of C and N storage under N deposition and the expansion of D. purpurea has a potential long-term negative impact on the ability of tundra plants to sequester C and N in the alpine tundra of the Changbai Mountains. These findings highlight how shifting plant expansion, through changes endogenous nutrients, can influence tundra litter decomposition and C and N storage responses to N deposition.

Keywords: C and N storage; Endogenous litter nutrients; Litter mass remaining; N deposition; Net N release.

MeSH terms

Ecosystem*
Nitrogen* / analysis
Nutrients
Plant Leaves / chemistry
Soil
Tundra

Substances

Soil
Nitrogen